The present invention relates to a recording/reproducing apparatus, and more particularly to a recording/reproducing apparatus suitable for storing audio and/or video data that is generally accessed sequentially.
In recent years, disk units such as hard disk units, optical disk units, magnetic optical disk units, etc. have been rapidly improved in its miniaturization, processing speed, multi-functional features, and price reduction. Particularly, the recording density per unit area of hard disks has been improved remarkably, and it now exceeded 10 Gbits per one inch square. Also, technical developments are currently under way in order to make it 100 Gbits per one-inch square in a few years. With such increasing recording density, the storage capacity per one disk unit has become a larger volume. Currently, a disk unit of 3.5 type with one-inch thickness with a 166 GB capacity has been achieved, and realization of 1 TB disk unit is no longer a dream in the future. Furthermore, it is considered that even a small disk unit of 1.0 type, for example, can have 100 GB capacity.
In recent years, by utilizing a larger volume of hard disk units, there are cases where audio and video data (AV data), is recorded in hard disks. For example, in the case of high-definition video data, the transfer rate is usually about 23 Mbps. Thus one-hour video data requires approximately the capacity of 23 Mbps×3600 s=10 GB or more. This means that it will become possible to store about 100-hour AV data in 3.5 type hard disk, and 10-hour AV data in 1.0 type hard disk in a few years. Of course, by reducing AV data in accordance with image resolution of the display unit, a recording period time is further increased.
However, the conventional hard disk units developed for recording personal computer data are not necessarily suitable for recording AV data. Thus, for example, in Japanese Patent Application Unexamined Publication No. 2001-118335, a proposal has been made that user' convenience for handling AV data is enhanced by defining areas for recording a piece of time-series continuous data (stream) on the hard disk, and accessing the data using the record area as a unit in consideration of a characteristic of AV data in which data completeness is not required for AV data as compared with computer data, whereas a certain amount of data needs to be handled continuously.
In the conventional hard disk units, when a defective sector occurs, the following skip processing or slip processing has been carried out, as in the past, in order to alternate another sector for the defective sector. By the processing disk units perform reading and writing data from the host while avoiding using the defective sector.
The skip processing is processing for substituting a sector prepared in reserve for a defective sector which has been no longer readable and/writable in the normal manner due to the defect occurred mainly after the factory shipment. For example, as shown in FIG. 2A, a servo sector 101 and a data sector 102 exist on a track n, and that sectors on a track m are kept for reserved sectors for alternation. When a defect occurs in a sector 103 having a physical sector number A+1 (logical sector number α+1), a sector 11 having a physical sector number A on a track m and kept in advance for a reserved sector for alternation is registered as a logical sector number α+1. By this processing, when a head 104 accesses data consecutively from a logical sector number a on the track n the head 104 moves to the track m at the position of the defective sector 103, accesses the alternation sector 11 having the logical sector number α+1, returns to the track n again, and accesses a sector having a logical sector number α+2 (physical sector number A+2).
On the other hand, as shown in FIG. 2B, the slip processing is processing for assigning a normal sector 1001 which is subsequent to the defective sector 103 with respect to physical allocation in place of the defective sector 103 into and from which data is not readable and/or writable in a normal manner due to a defect found at the inspection before the factory shipment. Specifically, when a sector with a physical sector number A+1, which is subsequent to a physical sector number A (logical sector number α), is the defective sector 103, a sector 1001 with a physical sector number A+2 becomes a logical sector number α+1.
Also, in Japanese Patent Application Unexamined Publication No. 04-023120, the following processing is disclosed: in an array disk unit in which a plurality of disks are used in an array, when an error is detected in data reading the data is corrected in real time to be sent to a host while storing the sector address in the disk unit as an error list. After the reading is complete, during the time when there is no command direction from the host, processing for substituting another sector for the defective sectors in the error list is performed.
Further, in Japanese Patent Application Unexamined Publication No. 08-255432, the following processing is disclosed: an address of a defective sector of which an error has been detected in data reading is stored in a storage unit, and alternation processing is performed when writing data into the defective sector by writing the data into a alternation area . By this processing, alternation processing is not carried out until writing is performed into a defective sector. Thus, if reading continues, reading from the original defective sector is repeated. It is described that a possibility of restoration of the data stored in the defective sector can be increased consequently, and thus reliability can be improved.
Furthermore, Japanese Patent Application Unexamined Publication No. 11-134809 discloses registration of addresses of the sectors at which reading errors occurred . Here, the registration of addresses is made by classifying the errors into three levels, depending on the time when the error is detected. The level 0 is an error sector address detected at shipping from factory, the level 1 is an error sector address detected when formatting by the user, and the level 2 is an error sector address detected when recording and reproducing usual user data . Also, in the recording area on the disk a user data area and a spare area (alternation area) are alternately arranged in advance. When writing data into the user area, registered error sectors are bypassed and writing is performed into the spare areas (alternation areas) by the slip processing. In this time, it is ensured that data is written in a predetermined number of sectors with respect to a pair of user data area and spare area.
AV data has a characteristic in which data completeness is not so much required, but the data is a large volume of time-series continuous data when compared to usual data for the personal computers or the like. However, current disk units employ a recording and reproducing method suitable for personal computers, etc. that require data completeness. In Japanese Patent Application Unexamined Publication No. 2001-118335 described above, recording by each piece of continuous data (stream) on the hard disk is disclosed. However, it does not disclose a mechanism of recording information about where each content of AV data is stored in disk unit. Thus the control method of the AV data content is not revealed. Also, in Japanese Patent Application Unexamined Publication No. 2001-118335 described above, it is not assumed that the AV data stream and the usual computer data with a small volume are recorded in a mixed manner.
Further, in accordance with the increase of recording density of disks, the number of sectors increases, thus it is considered that the number of sectors in which a defect occurs at subsequent stage will increase. If the alternation processing of the subsequently-occurred defective sector is performed by the conventional skip processing, the head needs to reciprocate to the reserved sector located at a physically remote position. Thus a possibility will arise that time runs out for the head movement when recording and reproducing time-series continuous AV data in a short response time. Furthermore, in the techniques of Japanese Patent Application Unexamined Publication No. 04-023120 and Japanese Patent Application Unexamined Publication No. 08-255432, the alternation processing of the defective sectors is the skip processing. Thus the above-described problem with the head movement arises. Moreover, in Japanese Patent Application Unexamined Publication No. 11-134809, the alternation processing of the defective sectors is the slip processing, however, it is necessary to allocate the user data area and the spare area(alternation area) alternately in the storage area in advance.